The term "optical disc" in the context of this specification refers to laser-readable discs for carrying, for example, prerecorded music, computer software, videos, films, interactive gases, or other data.
Optical discs are conventionally stored in plastic cases when not in use. Such discs typically include a central aperture that is used to both play the disc and to hold the disc in place during storage. Conventional plastic storage cases include a disc-engaging member centrally disposed within the case that projects through the aperture of the disc and secures the disc in place within the case. Such disc-engaging member is typically formed by a plurality of inwardly extending arms that are fixed to the case at their outer ends. At their inner ends, the arms extend upwardly, away from the base portion of the case to which the outer ends of the arms are secured, to form the disc-engaging member that fits within the central aperture of the disc.
In many prior disc holders, such as the disc holder disclosed in U.S. Pat. No. 5,788,068, the disc-engaging member defined by the unstressed arms is too large to fit within the central aperture of the optical disc. To fit the disc-engaging member of such disc holders within the central aperture of the disc, the disc-engaging member is first forced downwardly towards the base. This downward motion of the disc-engaging member bends the plurality of arms, thereby moving the inner ends of the arms closer together and reducing the dimension of the disc-engaging member, which permits the disc-engaging member to fit within the central aperture of the disc. After the pressure is removed from the disc-engaging member, the arms return to their unstressed position, and the disc-engaging member increases in dimension to tightly grip the rim of the central aperture of the disc. In the disc older disclosed in U.S. Pat. No. 5,788,068, as well as in other prior disc holders, the disc-engaging member has a lip defined by the arms curving slightly outwardly. After the pressure is released from the disc-engaging manner of such a prior disc holder, the central aperture of the disc is secured on the disc-engaging member between the of the central aperture and the base.
Prior disc holders such as the disc holder disclosed in U.S. Pat. No. 5,788,068 may suffer from a number of disadvantages stemming from the uneven distribution of force to the arms that define the disc-engaging member. This uneven distribution of force can easily occur as a result of an uncentered downward pressure being applied to the disc-engaging member. This uneven distribution of forces to the arms may have a number of undesirable consequences for both the disc holder and the disc. Specifically, when force is unevenly applied to the areas, some arms may be pushed downwardly towards the base to a sufficient extent to permit the portion of the lip defined by such arms to disengage from the disc. However, other arms may not be forced down sufficiently to disengage the portion of the lip defined by such arms from the disc. The user may nonetheless attempt to remove the disc from the case, resulting in the disc being bent, which may damage the disc and result in loss of information carried on the disc. Alternatively, the user may press down harder but in much the same way in an attempt to release the disc, thereby increasing the wear on the arms of the disc holder.
The uneven application of force to the disc-engaging member may also result in the premature wearing out of the arms that define the disc-engaging member. These arms are particularly subject to wear as a result of being unsupported at one end. Once some of the arms are worn out, the disc holder is essentially worn out as the upwards resilience of the arms is required for the disc holder to continue to function effectively--it is the upward resilience of the arms that secures the disc in place. If force is unevenly distributed among the arms, then it is likely that some arms will wear out long before other arms or other components of the disc holder do. This problem is self-perpetuating, as arms that have previously been subjected to more force may be weaker and may bend more in response to the same force than other arms. Even a force that is evenly applied initially may become uneven as different arms bend to different extent; the force may then be increasingly allocated to the arms that bend more, resulting in still more wear to these arms.
Thus a disc holder that favors the even distribution of the force between different arms and mitigates the uneven wearing of arms is desirable.